<!doctype html>
<html>
	<head>
		<meta charset="uft-8">
		<title></title>
		<style>
			#d1{
				width:501px;
				/*没写height*/
				border:2px solid #f00;
				float:left;
			}
			#d1 div{
				width:139px;
				height:100px;
				background:#990066;
				border:4px solid #00f;
				float:left;
			}
			#d3{
				margin:0px 30px;
			}
		</style>
	</head>
	<body>
		<div id="d1">
			<div id="d2"></div>
			<div id="d3"></div>
			<div id="d4"></div>
		</div>
	</body>
</html>